定义：
色散在传播方向上单调缓慢变化的光纤。

色散缓变光纤中色散（通常为正常色散）的大小在传播方向上逐渐减小。在光纤拉丝过程中通过逐渐改变光纤直径就能得到这一性质，因为光纤直径影响光纤中的波导色散。可以由标准单模光纤制作这种锥形光纤，也可以采用光子晶体光纤。 

色散缓变光纤的一个应用是绝热孤子压缩过程，其中利用了孤子脉冲参数（包括脉冲长度）随缓变的光纤参数发生绝热变化，前提是色散变化非常缓慢。

Definition: optical fibers where the chromatic dispersion changes monotonously along the propagation direction

More general term: optical fibers

Dispersion-decreasing fibers are optical fibers where the magnitude of the (typically anomalous) chromatic dispersion decreases along the propagation direction. Such a behavior can be obtained e.g. by gradually changing the fiber diameter during the fiber pulling process, because the fiber diameter affects the waveguide dispersion of the fiber. Such tapered fibers can be made of standard single-mode fibers, but also of photonic crystal fibers.

A possible application of dispersion-decreasing fibers is adiabatic soliton compression, where one exploits the fact that a soliton pulse adapts its parameters (including the pulse duration) to the fiber parameters, provided that the variation of dispersion is sufficiently slow.

Due to the difficulty of fabricating and handling dispersion-decreasing fibers, such fibers are not widely used.